<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body><div>Never mind about parsing. It looks like the parser is already doing what it needs to do and I need to look to RdrHsSyn.hs.</div><div><br></div><div><br></div><div><br></div><div id="composer_signature"><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><div style="font-size:85%;color:#575757">David Feuer</div><div style="font-size:85%;color:#575757">Well-Typed, LLP</div></div><div><br></div><div style="font-size:100%;color:#000000"><!-- originalMessage --><div>-------- Original message --------</div><div>From: David Feuer <david@well-typed.com> </div><div>Date: 1/15/18 2:10 PM (GMT-05:00) </div><div>To: Simon Peyton Jones <simonpj@microsoft.com> </div><div>Cc: ghc-devs@haskell.org </div><div>Subject: Implementing pattern synonym constructor signatures </div><div><br></div></div>Over the past week I've started digging into the code that implements pattern synonyms with an eye toward implementing the pattern synonym construction function signature proposal. I think I understand a decent amount of what's going on most places. However, I don't understand enough about type checking to have any idea about what needs to change where or how. There are several things that need to be addressed:<br>0. Parsing. I wasn't actually able to find the code that parses pattern synonyms. Can someone point me in the right direction?<br>1. When there is a constructor signature, it needs to be used for the construction function instead of the pattern signature. Can someone give point me in the right direction about how to do this?<br>2. When there is a constructor signature but no pattern signature, what should we do? I think "give up" sounds okay for now.<br>3. A pattern synonym without a constructor signature needs to be treated as it is today, so the machinery for matching things up needs to remain available.<br>David FeuerWell-Typed, LLP</body></html>